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 Title: |
US5883971:
System and method for determining if a fingerprint image contains an image portion representing a smudged fingerprint impression
[ Derwent Title ]
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| Country: |
US United States of America
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| Inventor: |
Bolle, Rudolf Maarten; Bedford Hills, NY
Pankanti, Sharathchandra Umapatirao; Mt. Kisco, NY
Yao, Yi-Sheng; Scarsdale, NY
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| Assignee: |
International Business Machines Corporation, Armonk, NY
other patents from INTERNATIONAL BUSINESS MACHINES CORPORATION (280070) (approx. 44,393)
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| Published / Filed: |
1999-03-16
/ 1996-10-23
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| Application Number: |
US1996000735718
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| IPC Code: |
Advanced:
G06K 9/00;
G06T 7/00;
Core:
more...
IPC-7:
G06K 9/00;
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| ECLA Code: |
G06K9/00A2; G06T7/00B;
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| U.S. Class: |
Current:
382/124;
382/115;
382/116;
382/125;
382/126;
382/263;
382/266;
382/272;
382/274;
Original:
382/124;
382/115;
382/116;
382/124;
382/125;
382/126;
382/263;
382/266;
382/272;
382/274;
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| Field of Search: |
382/115,124,125,126,116,274,266,263,272
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| Priority Number: |
| 1996-10-23 |
US1996000735718 |
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| Abstract: |
A fingerprint image is divided into blocks of pixels. The blocks are determined to be within the foreground or background of the image. Poor quality images are examined to determine if the imaging process is corrupted, e.g. by a wet finger, by determining if a smudginess measure is above a smudginess threshold. For each foreground block, a mean intensity (µ) of pixels is computed for those pixels whose intensities are smaller than the mean intensity of all pixels within the respective foreground block. Further the standard deviation (.cuberoot.) of intensities of all pixels within the respective foreground block is computed. For a foreground block with good contrast, µ is small and .cuberoot. is large. But for a block with low contrast due to smudginess, µ is small and .cuberoot. is small. Subsequently, to measure the contrast (a contrast measure) within a block, a function of the product (CS) of corresponding µ and corresponding .cuberoot. is determined. A comparison is then made to determine whether a block is a smudged block. If the contrast measure is smaller than a smudginess threshold STH1, then the block is classified as a smudged block. If not, the block is classified as a non-smudged block. Embodiment, STH1 is set to 0.12. Lastly, the smudginess measure as the ratio of the number of smudged blocks to total number of foreground blocks is computed. If the resulting ratio is larger than a second threshold, STH2, a smudged impression is reported.
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| Attorney, Agent or Firm: |
Percello, Louis J. ;
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| Primary / Asst. Examiners: |
Kelley, Christopher S; Chawan, Sheela
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| INPADOC Legal Status: |
Show legal status actions
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| Family: |
None
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First Claim:
Show all 16 claims |
We claim:
1. A system for determining whether fingerprint images contain smudged impressions comprising:
- a computer comprising at least one central processing unit, at least one memory, and at least one input device;
- at least one fingerprint image having a foreground and a background and being acquired by the input device and stored in the at least one memory, the at least one fingerprint image further comprising a plurality of blocks of pixels;
- a smudginess process that operates on said computer for determining a mean intensity of pixels within each foreground block of pixels, for determining a second mean intensity of pixels for those pixels within the respective foreground block of pixels whose intensities are less than the mean intensity, and for determining a standard deviation of intensities of all pixels within the respective foreground block of pixels, wherein a contrast measure is a function of a product of the determined second mean intensity and the determined standard deviation; and
- a comparator that determines that the foreground block of pixels is a smudged block if the contrast measure is less than a smudginess threshold, and that further determines that the image is a smudged image if a ratio of the number of smudged blocks to a total number of foreground blocks is greater than a second threshold.
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| Background / Summary: |
Show background / summary
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| Drawing Descriptions: |
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| Description: |
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| Forward References: |
Show 12 U.S. patent(s) that reference this one
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| Foreign References: |
None
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| Other Abstract Info: |
DERABS G1999-214319
DERABS G1999-214319
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| Other References: |
N. K. Ratha, S. Chen and A. K. Jain, "Adaptive Flow Orientation-Based Feature Extraction in Fingerprint Images," Pergamon, Pattern Recognition, vol. 28, No. 11, pp. 1657-1672, 1995.
(16 pages)
Cited by 22 patents
[ISI abstract]
B. M. Mehtre, "Fingerprint Image Analysis for Automatic Identification," R and D Division, CMC Limited, 115 Sarojini Devi Road, Secunderabad-500 003, India, Machine Vision and Application Springer-Verlag 1993.
D. H. Ballard and Christopher M. Brown, "Computer Vision--Region Growing," Department of Computer Science, University of Rochester, Rochester, NY, Prentice-Hall, Inc., Englewood Cliffs, NJ 07632, pp. 149-150, 1982.
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